We do a Climbing 101 class. the class is a 2 hour overview of types of climbing, grades, explanation of gear and it comes with a three week membership. We also teach top rope belay in the class. We set it up by appointment, one on one or with a group of friends.

Many gyms here use Meetup http://www.meetup.com. Some offer a reduced price and/free for the first time you attend. Folks are encouraged to take the intro class if they want to keep coming. Many do, and then they are regulars as well as belayers for newbies in future meetups. People come, then they want to bring friends and make it a social occaison. Its been wildly successful for some gyms, with multiple weekly meetups, others it seems to fall flat or attract only people who were coming anyway or those who come one time for a lark and never again.